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ITK-233Termodinamika Teknik

Kimia I

3 SKS

3 – Heat Effect & Thermochemistry

Sensible Heat

RCC

dVV

UdTCdU

)V,T(UU

igP

igV

TV

.....CyCyC

)DTCTBTA(RC

dPP

HdTCdH

)P,T(HH

igPBB

igPAA

igP

22igP

TP

mix

Heat Capacity Data - Gases

Heat Capacity Data - Gases

Heat Capacity Data – Solid

Heat Capacity Data - Liquid

Example 4.2

Calculate the heat required to raise the temperature of 1 mol of methane from 260 oC to 600 oC in a steady-flow process at a pressure sufficiently low that methane may be considered as an ideal gas

Example 4.3

What is the final temperature when heat in the amount of 0.4 x 106 Btu is added to 25 lbmol of ammonia at 500oF in a steady-flow process at 1 atm?

Latent Heat

Latent Heat

38.0

1r

2r

1T

2T

T1

T1

Watson Equation:

Standard Heat of Formation at 25oC & 1 atm

Standard Heat of Formation at 25oC & 1 atm

Standard Heat of Formation at 25oC & 1 atm

Standard Heat of Formation at 25oC & 1 atm

Heat of Reaction

The standard heat of reaction is equal to the algebraic sum of the standard heats of formations of the products minus the algebraic sum of the standard heats of formations of the reactants:

For reaction at the temperature of T:

tstanacRe

foductsPr

f0 HnHnHrxn

T

15.298

tstanreac,Pproducts,PrxnT,rxn dTnCnCHH0

Examples 4.6

Calculate the standard heat of the methanol synthesis reaction at 800 oC.

Example 4.7

What is the maximum temperature that can be reached by the combustion of methane with 20% excess of air?

Both methane & air enter the burner at 25 oC.

Example 4.8

One method for the manufacturing of ‘syngas’ is the catalytic reforming of CH4 with steam at high temperature and atmospheric pressure:

CH4(g) + H2O(g) CO(g) + 3 H2(g)

The only other reaction which occurs to an appreciable extent is the water-gas-shift reaction:

CO(g) + H2O(g) CO2(g) + H2(g)

If the reactants are supplied in the ratio of 2 mol steam/mol CH4, and if heat is supplied to the reactor so that the products reach a temperature of 1300 K, the CH4 is completely converted and the product stream contains 17.4% mol CO. Assuming the reactants to be preheated to 600 K, calculate the heat requirement for the reactor

Example 4.9

A boiler is fired with a high grade fuel oil (consisting only of hydrocarbons) having a standard heat of combustion of -43515 Jg-1 at 25oC with CO2(g) and H2O(l) as products. The temperature of the fuel and air entering the combustion chamber is 25oC. The air is assumed dry. The fuel gases leave at 300oC, and their average analysis (on a dry basis) is 11.2% CO2, 0.4% CO, 6.2% O2, and 82.2% N2.

Calculate the fraction of the heat of combustion of the oil that is transferred as heat to the boiler.

Problem 4.29

Methane gas is burned completely with 30% excess air at approximately atmospheric pressure. Both the methane and the air enter the furnace at 30oC saturated with water vapor, and the flue gases leave the furnace at 1500oC. The flue gases then passes through a heat exchanger from which they emerge at 50oC.

Per mole of methane, how much heat is lost from the furnace, and how much heat is transferred in the heat exchanger?

Problem 4.37

An equimolar mixture of nitrogen and acetylene enters a steady-flow reactor at 25oC and atmospheric pressure. The only reaction occurring is:

N2(g) + C2H2(g) 2 HCN (g)

The product gases leave the reactor at 600oC and contain 24.2 mol-% HCN.

How much heat is supplied to the reactor per mole of product gas?

Problem 4.41

A process for the production of 1,3-butadiene results from the catalytic dehydrogenation at atmospheric pressure of 1-butene according to the reaction:

C4H8(g) C4H6(g) + H2(g)

To suppress side reactions, the 1-butene feed stream is diluted with steam in the ratio of 10 moles of steam per mole of 1-butene. The reaction is carried out isothermally at 525oC, and at this temperature 33% of the 1-butene is converted to 1,3-butadiene.

How much heat is transferred to the reactor per mole of entering 1-butene?